Self-latching electric plug



Oct. 1, 1946.

FRANK SELF-LATCHING ELECTRIC PLUG 2 S heet-Sheet Filed Sept. 20, 1943 /7 TTOR/VEX Oct. 1, 1946. FRANK SELF-LATCHING ELECTRIC PLUG Filed Sept. 20, 1943 2 Sheets-Sheet 2 INVENTOR.

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Patented Oct. 1, 1946 UNITED STATES PATENT OFFICE SELF-LATCHING ELECTRIC PLUG Louis Frank, Fellows, Calif.

Application September 20, 1943, Serial No. 503,042

2 Claims. 1

My invention relates to electric plugs particularly of the type having two parts with contact prongs or fingers carried by one part, and. adapted to enter pockets or recesses in the other part, and the principal object of my invention is to provide plugs of the character referred to with simple means for automatically securing the parts to each other in assembled position and the securing means being cap able of convenient manual manipulation so as to enable the parts of the plug to be readily separated.

It Very frequently happens that the two part plugs used in current conductors to floor lamps, electrically operated machines, and electrically operated household equipment become accidentally separated due to pulling strains developed for one reason or another and impressed on the conduct-ors to which the plug parts are connected, and my invention is especially designed to prevent the accidental separation of the parts of the connecting plugs used in such conductors.

A further object of my invention is to provide two part electric plugs with latching means which is simple in Construction, inexpensive of manufacture and which may with little change be readily combined With the conventional forms of two part plugs now in general use.

With the foregoing and other objects in view, my invention consists in certain novel features of Construction and arrangement of parts which will be hereinafter more fully described and claimed and illustrated in the accompanying drawings, in which:

Fig. 1 is a top plan View of a two part plug equipped with my securing means.

Fig. 2 is a Vertical section taken approximately on the line 2-2 of Fig. 1.

Fig. 3 is a horizontal section taken approximately on the line 3-3 of Fig. 2.

Fig. 4 is a sectional View similar to Fig. 2 and showing a modified form of the securing means.

Fig. 5 is an elevational View of a part of a conventional electric socket and showing the same equipp d With means for securing the inserted prongs of a plug.

Fig. 6 is an enlarged vertical section taken on the line 6-6 of Fig. 5.

Fig. 7 is an enlarged detail section taken on the line 'l-T of Fig. 5.

Fig. 8 is a perspective View of a contact prong or nger and showing the same recessed for the reception of the securing means.

Fig. 9 show end elevational Views of contact prongs or fingers of different shapes.

Fig. 10 is a detail section showing a metal in- 2 sert which is engaged by the hook end of the latching means.

Fig. 11 is a top plan View of a two part plug and showing a modified form of the securing means.

Fig. 12 is a vertical section taken on the line 2 2 of Fig.11.

Fig. 13 is a vertical cross section taken on the line l3-|3 of Fig.11.

Referring by numerals to the accompanying drawings, and, particularly, Figs. 1, 2 and 3 which illustrate a preferred embodiment of my invention, u designates the plug member which carries a pair of spaced contact prongs or fingers ll) and which latter are adapted to enter openings !G in a, separately formed plug member I!) to engage contacts located in said member lil in accordance with conventional practice. Both parts II) and !0 of the plug are formed of insulating material. Plug member ll) i provided with the usual centrally arranged aperture ll for the accommodation of the electric conductors leading to said plug and a corresponding aperture z for conductors is formed in plug member o Formed in plug member u to one side of the center therein and in longitudinal alignment with one of the openngs la in plug member l0 is an opening 12, and formed in the upper portion of one of the side faces of said opening are recesses 18.

Fulcrumed at M on one of the prongs Ili which projects into the opening ln below said opening !2, is an arm l3 provided on it upper end with a head ll of insulation and projecting from the side face of said head and adapted to occupy either one of the notches s, is a lug IT Formed on the lower end of arm l3 is a hook !5 which is adapted to engage against a shoulder [6 formed in the upper end of a groove !6 which latter is formed in the plug member 10 along the lower portion of the opening lo therein.

Arm 13 is formed of resilient metal and under normal conditions with said arm lying fiat against the prong or finger u lug ll* occupies one or the other of the notches l8, thus maintaining hook |5 in or out of engagement with shoulder ls When the part of the plug are to be secured to each other in connected arrangement, arm [3 is manipulated and shifted into a neutral position on the prong In thus permitting both prongs carried by the plug member ll) to be inserted in the openings lu in plug member |0 and after such insertion, the head l'l on arm !3 is engaged and exed so as to withdraw lug 3 IT from the notch IB in which it rests and said arm l3 is swung upon its axis 14 thereby positioning hook !5 beneath shoulder e as illustrated in Fig. 2, and thus the parts of the plug are Secured in assembled relation.

In Fig. 4, an arm a practically identical with arm !3 and pivoted at M to one of the contact ngers, is rovided on its upper end with a head I'l of insulation and interposecl between the upper portion of said arm and the plug body o, at one side of the opening 12 therein is an expansive coi1 spring !9 which normally maintains said arm l3 in position so that the hook l on the lower end thereof is in engagement with the shoulder is In Figs. 5, 6 and '7, I have illustrated a conventional form of plug Connector which includes a body member B having internally arranged pairs of contact plates P for the reception of contact pins or fingers ZI carried by plug mernber 23. The upper portions of the contact fingers 2l are provided with an undercut shoulder or shoulders, such as 2 l A latching arm 20 is pivoted at 251 within plug body B, and the upper end of said arm, which projects through an opening in the upper portion oi plug body B is provided with a head 20 of insulation. A col spring 20 arranged between the upper portion of arm 20 and an adjacent portion of body B yieldingly resists outward swinging movement of the upper portion of said arm.

The lower end of arm Zi] terminates in a book 22, which passes through an aperture 22 formed in one of the contact plates P, and engages be neath shoulder 21 2 thus securing the parts oi' the plug coupling in assembled relation as illustrated in Figs. and 6.

To disengage hook 22 from its position beneath the shoulder z the head Zli on the upper end of arm is engaged and said arm is swung on g its axis so as to move hook 22 out of engagenent with the shoulder ZI and which action results from the hearing of the curved edge 22' of said hook with the edge of plate P to one side of the opening 22 therein. Inasmuch as arm ii] is formed of resilient metal, its lower portion may fiex outwardly when the releasing action as just described is accomplished.

In Fig. 8 I have shown a modified form of the contact prong or finger, and in this modification, the finger 24 is provided near its outer end with a recess 25 for the reception of the hcok 22 on the end of the arm 20.

In Fig. 9 I have shown a contact prong or finger 2| which is square in cross section, also a contact finger 2l which is oblong in cross section..

The modified Construction illustrated in Figs. 10, 11, 12 and 13 includes plug members and 3| and the external surface of member SI may be threaded for insertion in a threaded socket or provided with a threaded shell of such metal as 32. Formed in plug member 30 is a recess 33 in (See dotted lines Fig. 7.)

4 which is secured one end of a contact prong or finger 34 which latter projects through a slot into an opening 35 in plug member 3l.

Pivoted on the upper portion of finger 34 is an arm 35 provided on its upper end with a head 31 of insulation and projecting from said arm between said head and the pivot for said arm, is a nger 38 which bears on an expansive coil spring 33 seated in member 30 below the opening 33 therein. Formed on the lower end of arm 35 is a hook which, when the two parts of the plug are assernbled, engages beneath a shoulder 4! formed in the upper end of opening 33.

As a result of the Construction just described, the hook 49) Will engage beneath shoulder 4I when the two parts of the plug are assembled, thus securely maintaining the said parts in assembled relation, and to disconnect the parts of the plug, it is only necessary to engage head 31 and swing arm 36 against the resistance offered by spring 39 until hook 4!! is disengaged from shoulder 4l. Upper plug member 30 carries a contact finger 42, a companion to finger 34.

In Fig. 10 I have illustrated the shoulder 4| provided with a small insert 42 of metal located so that it is engaged by hook 40 when the parts of the plug are assembled, thus eliminating wear upon that particular portion of the shoulder with which the hook makes contact. This Construction may be used on the shoulders IE in the forms of plugs shown in Figs. 2 and 3.

Thus it will be seen that I have provided an electric plug part securing means which is simple in structure, inexpensive of manufacture and very effective in performing the i'unctions for which it is intended.

It will be understood that minor changes in the size, form and construction of the various parrts of my improved electric plug may be made and substituted for those herein shown and described without departing from the spirit of the invention, the scope of which is set forth in the appended claims.

I claim as my invention:

1. The combination with a two part electric plug Connector, one of the parts of which is provided with a contact finger, the other part being provided with an opening for the reception of said finger, of an arm pivoted on said contact nger, a hook on the lower end of said arm, there being a shoulder formed in the body of the member having said contact finger receiving opening, which shoulder is adapted to be engaged by said hook, a head of insulating material on the upper end of said arm, and there being recesses formed in the plug member carrying the prong for rcceiving a portion of said head and thereby main taining said arm in different positions.

2` I'he combnation as set forth in claim 1 with an insert of wear resisting material on that portion of the shoulder that receives said hook.

LOUIS FRANK. 

